<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
    <head>
        <!-- Book generated using mdBook -->
        <meta charset="UTF-8">
        <title>crate 和特性 - The Rust Rand Book</title>
        
        


        <!-- Custom HTML head -->
        


        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
        <meta name="description" content="Extended documentation for Rust&#x27;s Rand lib">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <meta name="theme-color" content="#ffffff" />

        
        <link rel="icon" href="favicon.svg">
        
        
        <link rel="shortcut icon" href="favicon.png">
        
        <link rel="stylesheet" href="css/variables.css">
        <link rel="stylesheet" href="css/general.css">
        <link rel="stylesheet" href="css/chrome.css">
        <link rel="stylesheet" href="css/print.css" media="print">

        <!-- Fonts -->
        <link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
        
        <link rel="stylesheet" href="fonts/fonts.css">
        

        <!-- Highlight.js Stylesheets -->
        <link rel="stylesheet" href="highlight.css">
        <link rel="stylesheet" href="tomorrow-night.css">
        <link rel="stylesheet" href="ayu-highlight.css">

        <!-- Custom theme stylesheets -->
        

        
    </head>
    <body>
        <!-- Provide site root to javascript -->
        <script type="text/javascript">
            var path_to_root = "";
            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
        </script>

        <!-- Work around some values being stored in localStorage wrapped in quotes -->
        <script type="text/javascript">
            try {
                var theme = localStorage.getItem('mdbook-theme');
                var sidebar = localStorage.getItem('mdbook-sidebar');

                if (theme.startsWith('"') && theme.endsWith('"')) {
                    localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
                }

                if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
                    localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
                }
            } catch (e) { }
        </script>

        <!-- Set the theme before any content is loaded, prevents flash -->
        <script type="text/javascript">
            var theme;
            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
            if (theme === null || theme === undefined) { theme = default_theme; }
            var html = document.querySelector('html');
            html.classList.remove('no-js')
            html.classList.remove('light')
            html.classList.add(theme);
            html.classList.add('js');
        </script>

        <!-- Hide / unhide sidebar before it is displayed -->
        <script type="text/javascript">
            var html = document.querySelector('html');
            var sidebar = 'hidden';
            if (document.body.clientWidth >= 1080) {
                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
                sidebar = sidebar || 'visible';
            }
            html.classList.remove('sidebar-visible');
            html.classList.add("sidebar-" + sidebar);
        </script>

        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
            <div class="sidebar-scrollbox">
                <ol class="chapter"><li class="chapter-item expanded affix "><a href="intro.html">介绍</a></li><li class="chapter-item expanded "><a href="guide-start.html"><strong aria-hidden="true">1.</strong> 入门指南</a></li><li class="chapter-item expanded "><a href="crates.html" class="active"><strong aria-hidden="true">2.</strong> crate 和特性</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="crates-rand.html"><strong aria-hidden="true">2.1.</strong> 随机加密(co)</a></li><li class="chapter-item expanded "><a href="crates-gen.html"><strong aria-hidden="true">2.2.</strong> 随机信号生成器</a></li></ol></li><li class="chapter-item expanded "><a href="guide.html"><strong aria-hidden="true">3.</strong> 指南</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="guide-data.html"><strong aria-hidden="true">3.1.</strong> 随机数据</a></li><li class="chapter-item expanded "><a href="guide-gen.html"><strong aria-hidden="true">3.2.</strong> 生成器类型</a></li><li class="chapter-item expanded "><a href="guide-rngs.html"><strong aria-hidden="true">3.3.</strong> 随机数生成器(RNGs)</a></li><li class="chapter-item expanded "><a href="guide-seeding.html"><strong aria-hidden="true">3.4.</strong> 为随机数生成器置种</a></li><li class="chapter-item expanded "><a href="guide-values.html"><strong aria-hidden="true">3.5.</strong> 随机值</a></li><li class="chapter-item expanded "><a href="guide-dist.html"><strong aria-hidden="true">3.6.</strong> 各种分布方式</a></li><li class="chapter-item expanded "><a href="guide-seq.html"><strong aria-hidden="true">3.7.</strong> 序列</a></li><li class="chapter-item expanded "><a href="guide-err.html"><strong aria-hidden="true">3.8.</strong> 错误处理</a></li></ol></li><li class="chapter-item expanded "><a href="portability.html"><strong aria-hidden="true">4.</strong> 可移植性</a></li><li class="chapter-item expanded "><a href="update.html"><strong aria-hidden="true">5.</strong> 更新</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="update-0.5.html"><strong aria-hidden="true">5.1.</strong> 更新到 0.5</a></li><li class="chapter-item expanded "><a href="update-0.6.html"><strong aria-hidden="true">5.2.</strong> 更新到 0.6</a></li><li class="chapter-item expanded "><a href="update-0.7.html"><strong aria-hidden="true">5.3.</strong> 更新到 0.7</a></li></ol></li><li class="chapter-item expanded "><a href="contributing.html"><strong aria-hidden="true">6.</strong> 贡献</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="contrib-doc.html"><strong aria-hidden="true">6.1.</strong> 文档</a></li><li class="chapter-item expanded "><a href="contrib-scope.html"><strong aria-hidden="true">6.2.</strong> Scope</a></li><li class="chapter-item expanded "><a href="contrib-test.html"><strong aria-hidden="true">6.3.</strong> 测试</a></li><li class="chapter-item expanded "><a href="contrib-bench.html"><strong aria-hidden="true">6.4.</strong> 基准</a></li></ol></li></ol>
            </div>
            <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
        </nav>

        <div id="page-wrapper" class="page-wrapper">

            <div class="page">
                
                <div id="menu-bar-hover-placeholder"></div>
                <div id="menu-bar" class="menu-bar sticky bordered">
                    <div class="left-buttons">
                        <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                            <i class="fa fa-bars"></i>
                        </button>
                        <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
                            <i class="fa fa-paint-brush"></i>
                        </button>
                        <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
                            <li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
                        </ul>
                        
                        <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                            <i class="fa fa-search"></i>
                        </button>
                        
                    </div>

                    <h1 class="menu-title">The Rust Rand Book</h1>

                    <div class="right-buttons">
                        <a href="print.html" title="Print this book" aria-label="Print this book">
                            <i id="print-button" class="fa fa-print"></i>
                        </a>
                        
                    </div>
                </div>

                
                <div id="search-wrapper" class="hidden">
                    <form id="searchbar-outer" class="searchbar-outer">
                        <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
                    </form>
                    <div id="searchresults-outer" class="searchresults-outer hidden">
                        <div id="searchresults-header" class="searchresults-header"></div>
                        <ul id="searchresults">
                        </ul>
                    </div>
                </div>
                

                <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
                <script type="text/javascript">
                    document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
                    document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
                    Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
                    });
                </script>

                <div id="content" class="content">
                    <main>
                        <h1><a class="header" href="#crates-and-features" id="crates-and-features">Crates and features</a></h1>
<h1><a class="header" href="#crates-和特性" id="crates-和特性">Crates 和特性</a></h1>
<blockquote>
<p><a href="https://github.com/rust-random/book/blob/master/src/crates.md">crates.md</a><br />
commit: 137d3179243735851dd1e73d154c671195881bd0 <br />
本章译文最后维护日期：2020-11-21</p>
</blockquote>
<p>Rand库由一组 crate 组成。其中 <a href="https://rust-random.github.io/rand/rand/index.html"><code>rand</code></a> crate 提供了主用户接口；如果需要其他的分布方式(distribution)，<a href="https://rust-random.github.io/rand/rand_distr/index.html"><code>rand_distr</code></a> 或 <a href="https://github.com/boxtown/statrs"><code>statrs</code></a> crate 可能会被派上用场。</p>
<p>这个库包含几个构建块：<a href="https://docs.rs/getrandom/"><code>getrandom</code></a> 与平台相关的随机数源接口，<a href="https://rust-random.github.io/rand/rand_core/index.html"><code>rand_core</code></a> 定义了生成器必须实现的API，而像 <a href="https://rust-random.github.io/rand/rand_chacha/index.html"><code>rand_chacha</code></a> 和 <a href="https://rust-random.github.io/rand/rand_xoshiro/index.html"><code>rand_xoshiro</code></a> 这类 crates 提供了多种伪随机信号生成器。</p>
<pre><code>getrandom ┐
          └ rand_core ┐
                      ├ rand_chacha ┐
                      ├ rand_hc     ┤
                      ├ rand_pcg    ┤
                      └─────────────┴ rand ┐
                                           ├ rand_distr
                                           └ statrs
</code></pre>
<h2><a class="header" href="#feature-flags" id="feature-flags">Feature flags</a></h2>
<h2><a class="header" href="#特性标志位" id="特性标志位">特性标志位</a></h2>
<p>Rand crate 允许通过特性标志位进行配置。请检查每个 crate 的 README文件以了解详情。</p>
<p>通过禁用默认特性：<code>rand = { version = &quot;0.7&quot;, default-features = false }</code>，大多数 Rand crate 都提供了对 no-std 模式支持。
但此特性的关闭还会受到以下标志位的影响：</p>
<!-- tobecheck -->
<ul>
<li><code>std</code> 选择依赖于 <code>std</code>库的相关函数</li>
<li><code>alloc</code>（启用 <code>std</code>模式会默认开启此特性）支持需要分配器(allocator)的函数（如果在 <code>no_std</code>模式中使用此特性时，Rand 需要 Rustc 1.36 或更高的版本）</li>
</ul>
<p>一些 Rand crate 可以支持以下第三方 crate：</p>
<ul>
<li><code>log</code> 允许通过 <a href="https://docs.rs/log/"><code>log</code></a> 记录一些日志消息</li>
<li><code>serde1</code> 支持通过1.0版的 <a href="https://serde.rs/"><code>serde</code></a> 来启用序列化数据对象</li>
</ul>
<p>请注意，加密型RNG<em>不</em>支持序列化，因为这可能存在安全风险。如果需要加密型RNG上的状态恢复功能，ChaCha生成器支持<a href="https://rust-random.github.io/rand/rand_chacha/struct.ChaCha20Rng.html#method.get_word_pos">获取并设置流位置</a>，它与随机种子(seed)一起使用可重建生成器的状态。<!-- tobocheck --></p>
<h2><a class="header" href="#wasm-support" id="wasm-support">WASM support</a></h2>
<h2><a class="header" href="#支持wasm" id="支持wasm">支持WASM</a></h2>
<p>几乎所有的 Rand crate 都是开箱即用的。只有 <code>rand_core</code> crate 在<a href="https://github.com/rust-random/getrandom#features">支持WASM功能时需要启用相关特性</a>。
因此，如果使用的是另一个依赖于 <code>rand_core</code> 的 crate（如大多数的 Rand crates），就必须显式地启用 <code>getrandom</code>特性才能正常工作。</p>

                    </main>

                    <nav class="nav-wrapper" aria-label="Page navigation">
                        <!-- Mobile navigation buttons -->
                        
                            <a rel="prev" href="guide-start.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                                <i class="fa fa-angle-left"></i>
                            </a>
                        

                        
                            <a rel="next" href="crates-rand.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                                <i class="fa fa-angle-right"></i>
                            </a>
                        

                        <div style="clear: both"></div>
                    </nav>
                </div>
            </div>

            <nav class="nav-wide-wrapper" aria-label="Page navigation">
                
                    <a rel="prev" href="guide-start.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                        <i class="fa fa-angle-left"></i>
                    </a>
                

                
                    <a rel="next" href="crates-rand.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                        <i class="fa fa-angle-right"></i>
                    </a>
                
            </nav>

        </div>

        

        

        

        
        <script type="text/javascript">
            window.playground_copyable = true;
        </script>
        

        

        
        <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="searcher.js" type="text/javascript" charset="utf-8"></script>
        

        <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="highlight.js" type="text/javascript" charset="utf-8"></script>
        <script src="book.js" type="text/javascript" charset="utf-8"></script>

        <!-- Custom JS scripts -->
        

        

    </body>
</html>
